This invention relates to multi-purpose film cassettes of the type in which a photographic film strip is exposed, processed and projected without removal from the cassette and, more particularly, it concerns a novel processing unit for such cassettes.
U.S. Pat. No. 3,641,896 issued to Rogers B. Downey et al on Feb. 15, 1972 and U.S. Pat. Nos. 3,778,140 and 3,800,306 issued respectively on Dec. 11, 1973 and Mar. 26, 1974 to Edwin H. Land contain exemplary disclosures of a motion picture system by which a supply of light sensitive film contained in a multi-purpose cassette can be exposed in a camera adapted to receive the cassette and then processed or developed to provide the conventional series of positive transparent image frames by placing the cassette in a viewing apparatus capable of activating a processor also contained in the cassette. Thus, once the film strip has been exposed, the image sequence recorded thereon may be viewed by projection after a time interval only as long as that required to rewind the film strip and during which the processing operation is performed.
Of the many components required for satisfactory operation of such systems, the film cassette and the processor contained therein are perhaps most critical. For example, the development of transparent image frames on the light sensitive emulsion of the film strip after exposure in the camera of the system requires the deposit of processing fluid on the film strip. This is accomplished by expressing processing fluid through an orifice to a moving run of the film strip during the processing cycle. After the processing fluid is released upon initiation of the processing cycle, it must be deposited uniformly across the width of the emulsion as well as uniformly along the full useful length of the film strip with a high measure of reliability inasmuch as any non-uniformity or discontinuity in the layer of processing fluid deposited on the film strip will result in undesirable blemishes plainly observable in the images to be viewed. When the processing operation has been completed, any excess processing fluid within the cassette must be secured against leakage to the overall cassette interior. Finally, provision is made in the cassette for indicating whether the film strip has been processed or not inasmuch as the operating mode of the viewing apparatus in which the cassette is inserted after exposure is different for a cassette containing an exposed unprocessed film strip than it is for the same cassette containing an exposed and processed film strip.
In addition to the functional importance of the cassette contained components in the operation of the system, the cassette is preferably a package for both the supply of film and the processing fluid from the point of manufacture to use by the consumer. The cassette also serves as a permanent container for the exposed and processed film strip during storage and subsequent projection cycles. In this respect, therefore, the processing components contained in the cassette can be considered as disposable in light of their being used only once with each cassette manufactured. This aspect of the cassette adds a still further requirement; that is, that the processing components be inexpensive and capable of mass production techniques without in any way detracting from operational performance in effecting the processing operation. Although the cassette structure illustrated in the above-mentioned U.S. patents as well as other patents and pending applications commonly owned by the assignee of the present invention have evidenced great potential from the standpoint of achieving system objectives, there is a need for simplification and corresponding cost reduction particularly in the once used cassette components which must be capable of mass production manufacturing techniques.